Functional Outcomes and Neurophysiological Assessment in Insular Glioma Resection

Introduction: Maximal safe resection of insular gliomas by preserving motor, language, and cognitive functions is critical in achieving improved patient outcomes. This study evaluates functional outcomes in patients undergoing resection of insular gliomas.

Methods: All patients underwent preoperative non-invasive mapping and function-based fiber tracking. Right-sided lesions were resected under general anesthesia, whereas left-sided lesions involved awake surgery when indicated by the surgical strategy. Neuropsychological assessments were conducted preoperatively, postoperatively, and at follow-up.

Results: Fourteen patients with insular gliomas (seven left-sided, seven right-sided) underwent microsurgical resection.
For right-sided lesions, mild postoperative impairments were observed in the Controlled Oral Word Association Test (COWAT) (12 [5–18]; 12 [4–19]) and Montreal Cognitive Assessment (MoCA) (28 [21–30]; 26 [18–30]), while more notable deficits were detected in the Trail Making Test B (TMT-B) (65 [45–96] sec; 89 [47–300] sec) and Nine-Hole-Peg Test (NHPT) (23 [18–27] sec; 26 [18–28] sec).
In patients with left-sided lesions, significant postoperative deficits, particularly in language functions, were observed in the COWAT (11 [7–17]; 4 [0–8]), MoCA (26 [24–29]; 20 [9–28]), and TMT-B (54 [34–117] sec; 168 [41–300] sec), with less pronounced effects in the NHPT (23 [16–24] sec; 25 [12–34] sec). Follow-up examinations in four patients showed improvement across tests, particularly in COWAT (11 [8–17]; 2 [0–8]; 6 [3–19]), MoCA (26 [24–29]; 21 [9–28]; 25 [19–30]), and TMT-B (53 [34–60] sec; 142 [41–300] sec; 66 [28–300] sec).

Conclusion : Postoperative impairments in right-sided lesions were observed primarily in executive function. Left-sided lesions demonstrated greater declines in performance, especially in language-related tasks; however, a gradual recovery was noted at follow-up. This study underscores the need for tailored surgical approaches based on lesion laterality to optimize functional outcomes.